This invention relates to formers on which magnetic coils may be wound and has particular reference to formers for intermetallic superconducting wires.
Intermetallic superconducting wires are now becoming available in which the superconductor is in the form of filamentary intermetallic, ie Nb.sub.3 Sn, compound. These wires have a limited radius through which they can be bent without damaging the intermetallic filaments. It is of course extremely well-known that intermetallic filaments are very brittle.
Conventionally, superconducting magnets are wound onto plastics formers using normal coil winding machinery. However, unless extreme care is taken during the winding operation, there is a danger that the wire will be bent to a radius small enough to cause damage to the intermetallic filaments. One way in which this can be prevented is to wind the wire green, ie unreacted, and to heat the wire on the former to a temperature greater than the minimum reaction temperature of the components of the intermetallic compound so as to form the intermetallic compound in situ on the coil.
However, using prior art formers of plastics material, the temperature needed to obtain a reaction is greater than the melting point of the former and thus the winding green option is not available.